1. Field of the Invention
The present invention relates to an apparatus and a method for adjusting an optical axis of headlight of a motorcycle, and to a motorcycle incorporating same. More particularly, the present invention relates to a motorcycle having a headlight optical axis adjustment apparatus, which is capable of automatically adjusting an optical axis of the headlight of the motorcycle in accordance with an attitude of a vehicle body of the motorcycle.
2. Description of the Background Art
There is a known headlight optical axis adjustment apparatus for a vehicle capable of automatically adjusting an optical axis of a headlight in accordance with a height or forward/rearward inclination of the vehicle. For example, a vehicle disclosed in the Japanese Patent Publication No. 3481014 includes an apparatus for adjusting a height of a seat fixed to the vehicle body frame, and for adjusting the optical axis of the headlight in accordance with the height of the seat.
Further, the Japanese Patent Application Publication No. 2005-350014 discloses a vehicle including a seating sensor and a vehicle height sensor for detecting a change in a height of an axle of a front wheel or a rear wheel of the vehicle. In the vehicle as disclosed in the Japanese Patent Application Publication No. 2005-350014, a vehicle attitude arithmetic unit computes a vehicle attitude based on signals received from the seating sensor and the vehicle height sensor. The vehicle attitude thus computed is used for adjusting an optical axis of the headlight.
When a motorcycle includes a system for automatically adjusting an optical axis in accordance with a height or a forward/rearward inclination of the motorcycle, the following points are required to be taken into consideration. Specifically, a motorcycle is provided with a center kickstand and a side kickstand, and a headlight of the motorcycle is often kept turned on while one of the kickstands is being used (is flipped down).
Here, since the rear wheel is off the ground when the center kickstand is being used, the state of the motorcycle becomes the same as the state in which the vehicle body is inclined in a forward direction, that is, the state in which the front wheel is at a lower position than a position of the rear wheel. Accordingly, in such case, the automatic optical axis adjustment apparatus may possibly be operated so as to change the optical axis of the headlight to be oriented in an upward direction.
On the other hand, when the side kickstand is used, a weight of the motorcycle is supported by three points. Accordingly, the load imposed on the front and rear wheels is reduced. Since a system for detecting vehicle attitude detects a vehicle attitude from compression and decompression conditions of suspension devices of the front and rear wheels, the reduction in the load imposed on the front and rear wheels causes the system to judge that a height of the vehicle is high. As a result, the automatic optical axis adjustment apparatus may be operated so as to adjust the optical axis of the headlight to be oriented in a downward direction.
The present invention has been made to overcome such drawbacks of the existing headlight optical axis adjustment apparatus for a motorcycle. Accordingly, it is one of the objects of the present invention to solve the aforementioned problems, and to provide a headlight optical axis adjustment apparatus for a motorcycle, which is capable of appropriately adjusting an optical axis of the headlight when a center kickstand or a side kickstand is used.